Transport tanks, which may be parts of tank containers, railway cistern wagons or tank trucks, often require a controlled temperature. It is specifically the lower tank zone that must be heated, for instance, when the tank is used for transporting masses which solidify at normal ambient temperatures, such as bitumen.
For heating by means of vapour, it has been known to form vapour channels welded under the lower zone of the tank and extending in the axial direction of the tank. The known design, however, requires a large amount of welding, causes welding stresses and results in a considerable increase of the tare weight.
In another design, a vapour space is formed by an outer shell which surrounds the lower zone of the tank jacket with a spacing therebetween. However, larger tanks must be supported by a container frame or vehicle frame not only in the region of the two tank ends but also at one or a plurality of intermediate locations in order to transmit vertical forces of the tank including its charge from the lower zone of the tank to the base structure of such frame.
A non-heated tank is known from U.S. Pat. No. 4,753,363, in which intermediate saddles are inserted between a reinforcing ring surrounding the tank jacket and a transverse bar of the base structure. In tanks having a heated lower zone, however, such reinforcing rings would interrupt the vapour chamber mentioned above. This causes portions of the tank jacket to be without heating and additionally requires measures to interconnect the separated vapour chamber portions. As a further essential disadvantage, any interruption of a vapour chamber formed by the outer shell would require additional welds.